Fixed
- Split expenses could not be edited after adding them — expense rows under Budget → Split were a static, non-interactive list. Each row is now a button that opens the expense dialog in edit mode (pre-filled with title, amount, payer, currency, date, split method, participants, and per-participant split values), with a delete action. The
PUT/DELETE /expenses/:idroutes already existed; only the frontend wiring was missing (#445).